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        <div style="margin: 0px 10px 8px 10px"  class="pagetitle">Constant Configuration</div>

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            <div id="ConfluenceContent"><p>Constants provide a simple way to customize a Struts application by defining key settings that modify framework and plugin behavior.  There are two key roles for constants.  First, they are used to override settings like the maximum file upload size or whether the Struts framework should be in "devMode" or not, and so on. Second, they specify which <a shape="rect" href="bean-configuration.html">Bean</a> implementation, among multiple implementations of a given type, should be chosen.  </p>

<p>Constants can be declared in multiple files.  By default, constants are searched for in the following order, allowing for subsequent files to override previous ones:</p>

<ol><li><a shape="rect" href="struts-defaultxml.html">struts-default.xml</a></li><li>struts-plugin.xml</li><li><a shape="rect" href="strutsxml.html">struts.xml</a></li><li><a shape="rect" href="strutsproperties.html">struts.properties</a></li><li><a shape="rect" href="webxml.html">web.xml</a></li></ol>


<p><img class="emoticon emoticon-warning" src="https://cwiki.apache.org/confluence/s/en_GB/5982/f2b47fb3d636c8bc9fd0b11c0ec6d0ae18646be7.1/_/images/icons/emoticons/warning.png" data-emoticon-name="warning" alt="(warning)"> The <code>struts.properties</code> file is provided for backward-compatiblity with WebWork.</p>

<h2 id="ConstantConfiguration-Constant">Constant</h2>

<p>In the various XML variants, the constant element has two required attributes: <code>name</code> and <code>value</code>.  </p>

<div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Attribute </p></th><th colspan="1" rowspan="1" class="confluenceTh"><p> Required </p></th><th colspan="1" rowspan="1" class="confluenceTh"><p> Description </p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p> name </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <strong>yes</strong> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> the name of the constant </p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p> value </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> <strong>yes</strong> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> the value of the constant </p></td></tr></tbody></table></div>


<p>In the <a shape="rect" href="strutsproperties.html">struts.properties</a> file, each entry is treated as a constant.</p>

<p>In the <a shape="rect" href="webxml.html">web.xml</a> file, any FilterDispatcher initialization parameters are loaded as constants.</p>

<h3 id="ConstantConfiguration-Sampleusage">Sample usage </h3>

<div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Constant Example (struts.xml)</b></div><div class="codeContent panelContent pdl">
<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;">
&lt;struts&gt;

  &lt;constant name="struts.devMode" value="true" /&gt;

  ... 

&lt;/struts&gt;
</pre>
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<div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Constant Example (struts.properties)</b></div><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">
struts.devMode = true
</pre>
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<div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Constant Example (web.xml)</b></div><div class="codeContent panelContent pdl">
<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;">

&lt;web-app id="WebApp_9" version="2.4" 
	xmlns="http://java.sun.com/xml/ns/j2ee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"&gt;

    &lt;filter&gt;
        &lt;filter-name&gt;struts&lt;/filter-name&gt;
        &lt;filter-class&gt;org.apache.struts2.dispatcher.FilterDispatcher&lt;/filter-class&gt;
        &lt;init-param&gt;
        	&lt;param-name&gt;struts.devMode&lt;/param-name&gt;
        	&lt;param-value&gt;true&lt;/param-value&gt;
        &lt;/init-param&gt;
    &lt;/filter&gt;

    ...

&lt;/web-app&gt;
</pre>
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